Tetrahydrofuran (tetrahydrofuran) is an industrially important solvent and monomer. It is prepared commercially from nonrenewable petrochemical feedstocks. With the potential depletion of the world's oil reserves, a need exists to develop a source of tetrahydrofuran from renewable sources such as biomass. Biomass comprises primarily a carbohydrate containing material. Biomass can also mean as comprising a polysaccharide material. It can also mean comprising cellulose, hemicellulose, or lignocellulose materials: for example, the biomass as obtained from wood, plants, residue from agriculture or forestry, organic component of municipal and industrial wastes, primary sludges from paper manufacture, waste paper, waste wood (e.g., sawdust), agricultural residues such as corn husks, corn cobs, rice hulls, straw, bagasse, starch from corn, wheat oats, and barley, waste plant material from hard wood or beech bark, fiberboard industry waste water, bagasse pity, bagasse, molasses, post-fermentation liquor, furfural still residues, aqueous oak wood extracts, rice hull, oats residues, wood sugar slops, fir sawdust, naphtha, corncob furfural residue, cotton balls, rice, straw, soybean skin, soybean oil residue, corn husks, cotton stems, cottonseed hulls, starch, potatoes, sweet potatoes, lactose, waste wood pulping residues, sunflower seed husks, hexose sugars, pentose sugars, sucrose from sugar cane and sugar beets, corn syrup, hemp, and combinations of the above. Carbohydrates offer a convenient starting material, with their multiple reactive hydroxyl groups, but a drawback of using most carbohydrates is the need to remove the unwanted hydroxyls.
1,2,3,4-Tetrahydroxybutane, shown below, is a 4-carbon sugar alcohol, or tetritol and can have three isomeric forms: erythritol, the meso form; D-threitol and L-threitol: 
Erythritol is used as a low calorie sweetener and sugar substitute and is typically produced commercially via the fermentation of corn starch. Threitol has limited commercial manufacture or use, but can be produced via modification of the equivalent isomer of tartaric acid.
U.S. Pat. No. 4,939,277 and Hudson et al. (J. Org. Chem. (1967), 32(11), p3650) both describe the acid catalyzed cyclodehydration of erythritol, and Montassier, et al., (J. Mol. Catal. (1991), 70(1), p65) describe the Ru/Cu catalyzed reaction. Produced is dihydroxytetrahydrofuran, but not tetrahydrofuran. Braca, et al, (J. Organomet. Chem. (1991), 417(1–2), p41) disclose less than 4% of tetrahydrofuran in the homogenous Ru catalyzed cyclodehydration of erythritol.
U.S. Pat. No. 6,013,812 describes a process for the cyclodehydration of a 4-carbon polyol in the presence of a supported metal catalyst, an acid catalyst and added water, producing a mixture of various hydroxylated cyclic ethers. U.S. Pat. No. 4,401,823 uses carbonaceous pyropolymer impregnated with a transition metal to hydrogenate polyols to produce a large variety of compounds. U.S. Pat. No. 4,313,884 prepares anhydropolyols from the corresponding polyols using various metal ions as catalysts; however no examples are described using either Re salts or erythritol.